Immunohistochemical and ultrastructural analysis of dysplastic epithelium of human ocular surface: Basement membrane and intermediate filament

Purpose. The dysplastic corneal epithelium is characterized by the abnormal proliferation of epithelial cells. The phenotypes of these cells have not been elucidated. We investigated whether such epithelium expresses the phen otypes of corneal or conjunctival epithelial cells, Methods, The corneas an d conjunctivae from four normal subjects and from one patient with epitheli al dysplasia of the central cornea were immunostained for N and VII collage ns and for cytokeratins. Monoclonal antibodies against collagen N reacted t o the [alpha 1(IV)](2)alpha 2(IV) or alpha 5(IV) molecule. Anti-cytokeratin antibodies were used to define epithelial cell types. The ultrastructure o f the basement membrane (BM) of each specimen also was examined. Results. T ype VII collagen immunoreactivity was detected in all the specimens of epit helial BM. The anti-collagen IV [alpha 1(IV)](2)alpha 2(IV) antibody labele d the conjunctival BMs, not the BMs of the corneal epithelia. of each subje ct. The normal corneal epithelial BM, not the BM of the conjunctival or dys plastic corneal epithelium, was immunolabeled with anti-alpha 5(IV) antibod y. The pattern of cytokeratin expression in the corneal epithelial dysplasi a resembled that seen in the normal conjunctivae. Small breaks in the BM of dysplastic corneal epithelium were ultrastructurally revealed. The number of hemidesmosomes in the dysplastic corneal epithelium was decreased as com pared with that in the normal BM. Conclusion. The composition of collagen t ypes within the BM and the cellular phenotype of the dysplastic epithelium in the cornea resembled those of conjunctival epithelium, not of the cornea .